Unusual groundcovers to break the lawn habit

Horseherb is a native deciduous herb that dies to the ground, then comes back strongly each spring.

Lawn grass is not the best choice for your landscape if you want to reduce water use, cope with shade, reduce maintenance requirements, address poor soils and maximize wildlife habitat. Consider one of the unusual groundcover alternatives instead of grass.

Last year I wrote about horseherb (straggler daisy) and its value as a wildlife plant and as a groundcover. The low-growing weed shows up in lawn areas that do not do a good job of supporting grass. In many neighborhoods in San Antonio it fills the gap in settings where the soil is thin and has become overly shaded as the oaks and other trees prospered more than the lawn grass.

Designating horseherb as a replacement for grass started out as a joke because, as a seeding perennial, the plant is almost impossible to control. It grows where lawn grass is not very successful and mows well, so the best compromise was to let the horseherb stay. In addition, horseherb is a favorite nectar source for the black swallowtails that decorate our landscapes year around, and it is a favorite browse choice of deer that are in many of our neighborhoods.

It turns out that horseherb has long been used as a groundcover in other habitats, so it was easy for area nurseries to supply transplants. Recognizing the value of this yellow-flowered, native plant as a butterfly nectar source, it was used as a groundcover in a popular certified butterfly garden.

This week in the garden

It is important to apply a pre-emergent herbicide capable of preventing both grassy and broad-leafed weeds at this time of the summer if you want to prevent winter weeds. Confer with your favorite nurseryperson to select the product that is right for you and your landscape.

Keep fall tomatoes watered and fertilized. They will quickly produce wider leaves and set fruit when the nighttime temperatures fall to 70 degrees.

Your zinnias and the other hot-weather annuals will keep blooming until Thanksgiving, but you can also plant cool-weather flowers such as stocks, dianthus, petunias, snapdragon and calendula in late September and October. Plan the transition.

Now, however it is nowhere to be seen because the other native, low-growing groundcover that was selected for the butterfly garden has completely covered the groundcover area: frog-fruit (Phyla nodiflora). Like horseherb, butterflies use the frog-fruit flowers for nectar. The butterflies, common streaky skippers and others, are smaller than the black swallowtails that use horseherb, but it is also used by buckeye and white peacock butterflies as a food source for their caterpillars.

As a groundcover the white-flowered frog-fruit grows to about 6 inches tall and makes an attractive but not overwhelming planting. Deer may browse the plant but not heavily. I have it growing in a sloped area near the street and in an open area that was a remnant compost pile. Both areas are well-drained, and neither is irrigated.

Unlike the horseherb which temporarily disappears during drought periods, the frog-fruit has been blooming attractively all summer. Transplants are available at some area nurseries, or frog-fruit can be transplanted from existing plantings by moving a piece of stem and root.

One of the best groundcovers for San Antonio landscapes is dwarf Mexican ruellia, also called dwarf Mexican petunia. It grows to about 1 foot tall with slender pointed leaves and violet, pink or white blooms. It will grow in sun or partial shade and is not a favorite of deer, who will only resort to it during a drought.

The plant is aggressive enough to fill in the space when planted every 18 inches, but it will not take over the neighborhood. Don’t mistake the dwarf version for full-size Mexican petunia because the latter will take over the neighborhood.

Most winters dwarf Mexican ruellia is evergreen, but during a winter with temperatures less than 20 degrees, it may freeze back but will regrow from the roots.

In my experience, the easiest way to establish a groundcover is to spray the designated area with a glyphosate product (Round-up) to kill the current grass or weeds. When the spayed area turns from green to brown, you can mow it and then plant the new groundcover transplants right into the killed sod, which serves as a mulch for the new plantings.

If you are a SAWS customer and you replace lawn with groundcovers like dwarf ruellia, you are eligible for a rebate if you meet the requirements outlined on its website, gardenstylesanantonio.com, for the newest water saver coupon.

Gardeners, from 9:30-11 a.m. Sept. 8, I will lead a free class about the winter garden at the Dreamhill Estates Education Resource Center, 6800 Dorothy Louise Drive. Attendees will receive a broccoli transplant as a start for their winter garden. 210-775-1824.